Online Photo Diagnosis

May 1, 2009

Online Photo Diagnosis

By William Townsend, OD, FAAO

This 23-year-old male presented with complaints of recent-onset moderate bilateral ocular discomfort. He had a history of keratoconus since his late teens, and he successfully wore SynergEyes lenses (SynergEyes, Inc.). His presenting visual acuities were 20/20 in both eyes. Slit lamp examination showed well fitting lenses that moved slightly with blinking. Striae characteristic of keratoconus had been previously noted and were still present OU. The corneas demonstrated multiple scattered punctate lesions that appeared to be epithelial and subepithelial layers. Scant staining with fluorescein was noted on some of the lesions.

The bulbar conjunctiva showed grade 1+ injection, and the tarsal conjunctiva exhibited no follicles and grade 1+ papillae. Palpation of the preauricular nodes did not demonstrate tenderness or adenopathy. I diagnosed Thygeson's superficial punctate keratitis (TSPK).

Based on the size and location of the lesions, the lack of pain and adenopathy, and the absence of follicular hypertrophy, I prescribed topical prednisolone acetate 1% ophthalmic suspension every six hours. Within one week he showed significant improvement in comfort but minimal change in the appearance of the lesions. I began tapering the steroid and added cyclosporine A 0.05% every 12 hours. At his most recent visit, six months after the onset of the disease, the patient was doing very well with only trace residual evidence of the lesions. He continues to wear contact lenses successfully, and I plan to reduce and eventually discontinue therapy provided there is no exacerbation of the keratitis.

Thygeson first described the condition that now bears his name in 1950. He reported cases of a transient, bilateral superficial punctate keratitis with coarse corneal epithelial opacities and no stromal involvement. TSPK is an insidious and chronic condition with minimal pain that may last for months or years. It may spontaneously regress and then recur over a period of years.

The precise pathophysiology of TSPK is still in question. It has been associated with viral disease, and LASIK procedures; there is a significant association between TSPK and HLA-DR3, suggesting that this histocompatibility antigen may in some way alter the immune status of individuals who have TSPK. Cheng et al (2004) evaluated TSPK lesions in a 56-year-old male using confocal microscopy. Their study revealed that the affected tissue in the epithelium contains clumps of enlarged epithelial cells that were approximately twice as large as the cells in normal tissue. Hyper-reflective cell margins are typical of desquamating epithelial cells, but these are found deeper in tissue. Scans of tissue in the region of Bowman's layer revealed multiple highly reflective filamentary structures with distinctive branching patterns. No inflammatory cells were noted.

Various therapies and procedures have been used with varying degrees of success in the management of TSPK. Debridement of the cornea is unsuccessful; once the epithelium grows back, the lesions often recur. Steroids have been a mainstay of treatment for many years, and fluorometholone and other steroids of limited efficacy have worked well in many cases. Recalcitrant cases may respond as well or even better to topical cyclosporine A than to steroids, which also minimizes the risk factors associated with chronic steroid use. Bandage contact lenses may also be effective during the active course of the disease.